Hydraulic oil pump



Jan. 6, 1948. P. s. MEFFERD nynnwmc 011, mm

" Filed March 14, 1946 2 Sheets-Sheet 2 rr nusv I vPatented Jan. 6, 1948 Paul S. Meilerd, Laurens, Iowa Application March 14, 1946, Serial No. 654,418

My invention relates to a hydraulic oil pump.

An object of my invention is to provide a hydraulic oil pump which can be attached to a tractor power take of! shaft, or to any other driving portion of the tractor, and which can also if desired, be attached to other driving arrangements.

A further object of my invention is to provide an oil pump which is eflicient in operation, which,

is compact, and which includes certain valved arrangements whereby such arrangements will operate both during operating pressure conditions as well as when the oil is being returned to its reservoir.

v A further object of my invention is to provide a combined pump and reservoir in one integral unit.

A further object of my invention is to provide an easily operable control arrangement for controlling the pump during the power cycle, as well as the return cycle.

A further object of my invention is to provide a synchronized valve arrangement which in returning oil during the release cycle will be adjusted in its rate offlow so that abrupt stoppages in any parts of the oil circuit will not aifect the operation of the arrangement.

A further object of my invention is to provide a special valve control having by-pass features so that the valve will allow uniform adjustment of the power desired and will further provide means for allowing exhaustion of the oil back to its reservoir after the power cycle.

A further object of my invention is to provide an oil pump having the above characteristics, which will also allow control of a hydraulic cir-' cult and still allow the rotatable pump elements to run during such control.

A further object of my invention is to provide a special plunger valve having features wherein the control lever of the arrangement will be brought back to normal position without requiring the use of springs and so forth.

A further object of my invention is to provide all of the above objects in a simple construction.

With these and other objects in view, my invention consists in the construction, arrangement,

' and combination of the various parts of my device, whereby the objects contemplated are at-' tained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawingsin which:

Figure 1 is a sectional view of the pump taken 4 Claims. (Cl. 103-41) Figure 2 is a sectional view of Figurel taken substantially along the lines 2-2 thereof.

Figure 3 is a sectional detail taken along the lines 3-3 of Figure 1, a

' Figure 4 is a forward elevation of the unit,

Figure 5 is a, side view of Figure 4, and

Figure 6 is a detail of one of the valves.

I have used the character ill to designate the rear wall of a reservoir having the top wall H, the bottom wall l2 and the forward opening l3 adjacent to the flanges M. The character [5 designates the side walls of the reservoir which reservoir is adapted to receive an oil supply [6. Attached by means of suitable bolts I! to the flanges i4 is a square plate l8 which plate includes corner bosses I9 into which are received the studs 20. The rear wall III also includes similar bosses and studs i9 and 20. Attached by means of the bolts 21 to the forward plate I8 is a casting 22 which is securely retained against the thin gasket 23. The casting 22 includes a lower portion 24 which includes the partially cylindrical openings at 25 and 26, in which are positioned the snugly engaged pump members 21 and 28, the member 21 being keyed at 29 to the shaft 30. Both gear members include the interengaging teeth 31 for forcing the oil in the desired direction, the gears being driven in the direction of the arrows 32.

The gear 21 is the driving ear which is driven by the shaft, and the gear 28 is the driven gear driven by the gear 21. The shaft is suitably journaled at 33 within a bushing 34 which is secured within the portion 35 of the casting. The gear 28 includes a bushing 36 which rotates upon a short shaft 31 which extends into a suitably bushed socket within the plate portion 38 (see Fig. 4), and which is suitably journaled at the rear thereof in a further portion 35.

Extending through the bottom of the casing portion 24 is an oil inlet opening 39 which communicates to the pump elements as shown and a further opening 40 communicates with a cylindrical cavity 4| which terminates in a rear wall 42, and the rear wall 42 includes a cylindrical opening 43 which communicates to the oil in .ber 45' includes a'shoulder adapted to register with the seat 44, The plunger 45 also includes the slotted end at 5| through which is received substantially along 'the lines l-l of Figure 2,

a pin 52, the pin- 52. being received within the elongated slot 53 formed in the end 54 of a control lever 55 which is pivoted at '54 between the pair of raised bosses 51, the lever 55 being slightly pitched from the vertical as shown in Figure 4 and extending into the end handle portion 58.

Communicating with the cylindrical cavity 4| is an opening 59 which communicates with a further opening 60 having a valve seat at 8| against which the valve 62 is adapted to bear. Attached to the valve 62 at 63 is the valve control rod 64 which passes through the packing ring 65 secured by the washers B6; The end of the rod 64 bears against alever member 61 which is pivoted at 68 to the outwardly extending boss 89 which is attached to the plate IS, the member 61 being inclined angularly as shown. Threadably secured at I is a relief valve member ll having the openings I2 and the threadably engaged end nut 13 which includes an opening 14 which receives a pin 15 which is attached to the valve 16 which is held against the valve seat 11 by means of the compression spring 18.

This valve serves to protect the oil circuit against excessive pressure, such pressure being passed through the opening 19. A further spring 80 is received between the opening I9 and the valve 62. Communicating at Bi with the opening is a further port 82 which communicates at 83 with a further opening 84 which passes forwardly and communicates with the opening 85 provided in the forward plate l8. The end of the pipe line which communicates to the apparatus to be operated, is indicated generally by the character 85 which can be attached at 81 to the boss 88 which boss is attached to the plate l8. The pipe 86 can pass to a hydraulic cylinder including a piston for lifting purposes, or can be attached to any other type of hydraulic power circuit. The reservoir containing the pump can be attached to the'tractor by means of the extending studs 20 in any suitable manner, the shaft 30 can be the power take-off shaft of the tractor, or can be atiached to the power take-off shaft by means of any suitable coupling and the like.

The shaft 30 is suitably packed in a packing ring 89 which ring is received in the boss 90. An opening 9i communicates from the space 92 next to the packing to the inside of the plate is and between the gears 21 and 28 to entrap and return excess oil attempting to pass out of the packed shaft joint.

Now that I have described the structure of my device I shall explain the operation thereof.

When it is desired to apply power to the hydraulic circuit by means of oil pressure, the lever 55 is in the position shown in Figure 2 or Figure 5. When the lever is in this position the opening 43 is blocked or closed by means of the extending portion 93 of the plunger 45, as well as by the shoulder 50 against the seat 44. The oil which is forced upwardly through the opening 59, into the opening 60 where such oil pressure will force the valve 52 open, the oil then continuing through the port 82, thence through the port 84 and out through the pipe 8'6 into the circuit where the work is to be performed.

For releasing the pressure completely and to allow the oil in the circuit to pass backwardly into the reservoir, the lever 55 is pushed forwardly in the direction of the arrow in Figure 2. This action causes the plunger to be pulled outwardly with the portion 93 being ,pulled out of the opening 43 and the seating surfaces and 44 to be disengaged, which causes the oil from the pump to pass directly into the reservoir. As the lever is forced inwardly, it will also bear against the end 94 of the lever member 81, which forces the valve 52 inwardly allowing the oil in the system to return in the reverse manner at the same time, where it also exhausts into the reservoir. In this manner the control of the upper and lower ports are synchronized so that the oil will pass at a uniform rate, so that sudden stoppages in the oil circuit or pump will not cause shock to the entire hydraulic system, eliminating the danger of breakages and so forth. It will also be seen that this arrangement allows operation of the circuit while the pump is continuously rotating.

It will be noted from Figure 6 that the oil pressure passing upwardly and downwardly will act against the shoulder 50 of the plunger 45 forcing the lever 55 to normalposition, without the use of springs and the like, the annular shoulder thereby providing this advantage as well as an eflicient valve seat.

It will now be noted that I have provided a compact unit oil pump having the various advantages mentioned in the objects of my invention with further advantages being readily apparent.

Some changes may be made in the construction and arrangement of the parts of my invention without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim as my invention:

l. A hydraulic oil pump comprising a reservoir, a pump unit attached within said reservoir, said pump unit having an outletcommunicating from the pump exteriorly of the reservoir, means for causing flow of oil in said reservoir to pass through'said outlet under pressure developed by said pump unit, said pump unit including by-pass means for providing return of oil pumped into said outlet incidental upon control of an operator, said by-pa'ss means including a cavit communicating into said reservoir, 3, plunger normally seating against said cavity whereby movement of said plunger away from said cavity will cause oil to pass into the reservoir, a control lever pivotally attached to said pump .unit and to said plunger for operating the plunger, a. cavity of substantially greater diameter than said plunger in which said plunger is mounted, ports communicating fromsaid larger cavity to said outlet, a valve controlling said ports, said valve having a stem extending outwardly of said unit, said control lever adapted to force said stem and valve inwardly to open said ports when said plunger is moved outwardly.

2. A hydraulic oil pump comprising a reservoir, a pump unit attached within said reservoir, said pump unit having an outlet communicating from the pump eXteriorly of the reservoir, means for causing flow of oil in said reservoir to pass through said outlet under pressure developed by said pump unit, said pump unit including by-pass means for providing return of oil pumped into said outlet incidental upon control of an operator, said bypass means including a cavity communicating into said reservoir, a plunger normally seating against said cavity whereby movement of said plunger away from said cavity will cause oil to pass into the reservoir, a control lever pivotally attached to said pump unit and to said plunger for operating the plunger, a cavity of substantially greater diameter than said plunger in which said plunger is mounted, ports communicating from said larger cavity to said outlet, a valve controlling said ports,

said unit, said control-lever adapted to force said stem and valve inwardlyto open said ports when said plunger is moved outwardly, said plunger receiving cavity having an annular shoulder, said plunger having a shoulder registering with said annular shoulder, the shoulder on said plunger being adapted to'provide pressure means against the pump exteriorly of the reservoir, means for causing flow of oil in said reservoir to pass through -said outlet under pressure developed by said pump unit, said pump unit including by-pass means for providing return of oil pumped into said outlet incidental upon control of an operator, said bypass means including a cavity communicating into said'reservoir, a plunger normally seating against said cavity whereby movement of said plunger away from said cavity will cause oil to pass into the reservoir, a control lever pivotally attached to said pump unit and to said plunger for operating the plunger, a cavity of substantially greater diameter than said plunger in which said plunger is mounted, ports communicating from said larger cavity to said outlet, a valve controlling said ports, said valve having a stem extending outwardly of said unit, said control lever adapted to force said stem and valve inwardly to open said ports when said plunger is moved outwardly, said plunger receiving cavity having an annular shoulder, said plunger having a shoulder registering with said annular shoulder, the shoulder on said plunger being adapted to provide pressure means against said plunger to return the control lever to normal position, said pump unit including engaged pump gears, one of said gears being a driving gear, an opening communicating from said gears to said larger cavity,

4. A hydraulic oil pump comprising a reservoir, a pump unit attached within said reservoir, said pump unit having an outlet communicating from the pump exteriorly of the reservoir, means for causing flow of oil in said reservoir to pass through said outlet under pressure developed by said pump unit, said pump unit including by-pass means for providing return of oil pumped into said outlet incidental upon control of an operator, said bypass means including a cavity communicating intosaid reservoir, a. plunger normally seating against said cavity whereby movement of said plunger away from said cavity will cause oil to .pass into the reservoir, a control lever pivotally attached to said pump unit and to said plunger for operating the plunger, a cavity of substantially greater diameter than said plunger in which said plunger is mounted, ports communicating from said larger cavity to said outlet, a valve controlling said ports, said valve having a stem extending outwardly of said unit, said control lever adapted to force said stem and valve inwardly to open said ports when said plunger is moved outwardly, said plunger receiving cavity having an annular shoulder, said plunger having a shoulder registering with said annular shoulder, the shoulder on said plunger being adapted to provide pressure means against said plunger to return the control lever to normal position, said pump unit including engaged pump gears, one of said gears being a driving gear, an opening communicating from said gears to said larger cavity, a lever member normally abutting against said valve stem,

said control lever adapted to force said lever member and said valve stem upon movement of said control lever.

PAUL S. MEFFERD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATEN'I'S 

